The present invention relates to a vehicle-mounted radar apparatus.
As a conventional vehicle-mounted radar apparatus, an apparatus such as the one shown in FIGS. 5 and 6 is known.
FIG. 5 is a schematic diagram illustrating a conventional vehicle-mounted radar apparatus, and FIG. 6 is a plan view thereof. In the drawings, the direction of a radar head unit 12 including a beam-radiating means is rotated in a reciprocating manner with a fixed pattern by a mechanical control unit 11 serving as a scanning means, thereby allowing the beam-radiating direction to change to left and right. A reference-position detecting unit 13 serving as a reference-position detecting means detects the arrival of the direction of the beam at a reference direction (the position indicated by the two-dotted dash line in FIG. 6) by detecting a pawl portion 12a formed integrally with the radar head unit 12, and the position of the reference-position detecting unit 13 is made adjustable. An ECU 14 includes an angle-calculating means for calculating the direction of the beam on the basis of the time counted by a time counter 15 serving as a time-counting means for counting the elapsed time.
As the reference-position detecting unit 13 serving as the reference-position detecting means, it is possible to use a photointerruptor as shown in FIG. 6, and the photointerruptor is capable of detecting the pawl portion 12a by means of an electron beam which is emitted from a light-emitting element 16 toward a light-receiving element 17.
Next, a description will be given of the operation of the conventional apparatus configured as described above. The direction of the radar head unit 12 is continuously changed in a reciprocating manner by the mechanical control unit 11, thereby effecting the so-called scanning. During this scanning process, when the pawl portion 12a formed integrally with the radar head unit 12 has reached the position of the reference-position detecting unit 13, the output of the reference-position detecting unit 13 is turned on, and the time counter 15 is thereby reset.
When a reflected beam from an object to be detected is detected, the ECU 14 converts the counted result, measured by the time counter 15, into an angle by means of the angle-calculating means on the basis of a preset conversion table, and outputs the same as the angle of the object to be detected.
In addition, the ECU 14 causes the beam to be radiated in pulses by effecting on/off control of beam radiation, and outputs the distance to the object to be detected by such as counting the time from the time of beam radiation until the detection of the reflected beam.
With this conventional vehicle-mounted radar apparatus, in order to allow the frontal direction of the vehicle to coincide with the direction in which an angle output value of the apparatus equals 0, the angle output value is conventionally adjusted by moving the position of the reference-position detecting unit 13 during the operation of mounting the apparatus in the vehicle.
Since the conventional vehicle-mounted radar apparatus is configured as described above, there has been a problem in that, in making adjustment such that the angle output value equals 0 when the frontal direction of the vehicle and the direction of the radar head unit coincide with each other, the position of the aforementioned reference-position detecting unit needs to be moved for each apparatus, thereby making the angle adjustment operation troublesome.